public sealed class HttpCookie
{
    // 获取或设置将此 Cookie 与其关联的域。默认值为当前域。
    public string Domain { get; set; }
    // 获取或设置此 Cookie 的过期日期和时间（在客户端）。
    public DateTime Expires { get; set; }
    // 获取一个值，通过该值指示 Cookie 是否具有子键。
    public bool HasKeys { get; }
    // 获取或设置一个值，该值指定 Cookie 是否可通过客户端脚本访问。
    // 如果 Cookie 具有 HttpOnly 属性且不能通过客户端脚本访问，则为 true；否则为 false。默认为 false。
    public bool HttpOnly { get; set; }
    // 获取或设置 Cookie 的名称。
    public string Name { get; set; }
    // 获取或设置要与当前 Cookie 一起传输的虚拟路径。默认值为当前请求的路径。
    public string Path { get; set; }
    // 获取或设置一个值，该值指示是否使用安全套接字层 (SSL)（即仅通过 HTTPS）传输 Cookie。
    public bool Secure { get; set; }
    // 获取或设置单个 Cookie 值。默认值为空引用。
    public string Value { get; set; }
    // 获取单个 Cookie 对象所包含的键值对的集合。
    public NameValueCollection Values { get; }
    // 获取 System.Web.HttpCookie.Values 属性的快捷方式。
    public string this[string key] { get; set; }
}

HttpCookie cookie = new HttpCookie("MyCookieName", "string value");
Response.Cookies.Add(cookie);

HttpCookie cookie = Request.Cookies["MyCookieName"];
if( cookie != null )
    labCookie1.Text = cookie.Value;
else
    labCookie1.Text = "未定义";

HttpCookie cookie = new HttpCookie("MyCookieName", null);
cookie.Expires = new DateTime(1900, 1, 1);
Response.Cookies.Add(cookie);

public class DisplaySettings 
{
    public int Style;

public int Size;

public override string ToString()
{
return string.Format("Style = {0}, Size = {1}", this.Style, this.Size);
}
}

private void WriteCookie_2a()
{
    DisplaySettings setting = new DisplaySettings { Style = 1, Size = 24 };

HttpCookie cookie = new HttpCookie("DisplaySettings1");
cookie["Style"] = setting.Style.ToString();
cookie["Size"] = setting.Size.ToString();

Response.Cookies.Add(cookie);
}

private void ReadCookie_2a()
{
HttpCookie cookie = Request.Cookies["DisplaySettings1"];
if( cookie == null )
labDisplaySettings1.Text = "未定义";
else {
DisplaySettings setting = new DisplaySettings();
setting.Style = cookie["Style"].TryToInt();
setting.Size = cookie["Size"].TryToInt();
labDisplaySettings1.Text = setting.ToString();
}
}

private void WriteCookie_2b()
{
    DisplaySettings setting = new DisplaySettings { Style = 2, Size = 48 };

HttpCookie cookie = new HttpCookie("DisplaySettings2", setting.ToJson());
Response.Cookies.Add(cookie);
}

private void ReadCookie_2b()
{
HttpCookie cookie = Request.Cookies["DisplaySettings2"];
if( cookie == null )
labDisplaySettings2.Text = "未定义";
else {
DisplaySettings setting = cookie.Value.FromJson<DisplaySettings>();
labDisplaySettings2.Text = setting.ToString();
}
}

/// <summary>
/// 将一个对象序列化成 JSON 格式字符串
/// </summary>
/// <param name="obj"></param>
/// <returns></returns>
public static string ToJson(this object obj)
{
    if( obj == null )
        return string.Empty;

JavaScriptSerializer jss = new JavaScriptSerializer();
return jss.Serialize(obj);
}

/// <summary>
/// 从JSON字符串中反序列化对象
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="cookie"></param>
/// <returns></returns>
public static T FromJson<T>(this string cookie)
{
if( string.IsNullOrEmpty(cookie) )
return default(T);

JavaScriptSerializer jss = new JavaScriptSerializer();
return jss.Deserialize<T>(cookie);
}

<input type="button" onclick="WriteCookie();" value="WriteCookie" />

<script type="text/javascript">
function WriteCookie() {
var cookie = "cookie_js=22222222; path=/";
document.cookie = cookie;
}
</script>

<input type="button" onclick="ReadCookie();" value="ReadCookie" />

<script type="text/javascript">
function ReadCookie() {
alert(document.cookie);
}
</script>

/**
 * Create a cookie with the given name and value and other optional parameters.
 *
 * @example $.cookie('the_cookie', 'the_value');
 * @desc Set the value of a cookie.
 * @example $.cookie('the_cookie', 'the_value', {expires: 7, path: '/', domain: 'jquery.com', secure: true});
 * @desc Create a cookie with all available options.
 * @example $.cookie('the_cookie', 'the_value');
 * @desc Create a session cookie.
 * @example $.cookie('the_cookie', null);
 * @desc Delete a cookie by passing null as value.
 *
 * @param String name The name of the cookie.
 * @param String value The value of the cookie.
 * @param Object options An object literal containing key/value pairs to provide optional cookie attributes.
 * @option Number|Date expires Either an integer specifying the expiration date from now on in days or a Date object.
 *                             If a negative value is specified (e.g. a date in the past), the cookie will be deleted.
 *                             If set to null or omitted, the cookie will be a session cookie and will not be retained
 *                             when the the browser exits.
 * @option String path The value of the path atribute of the cookie (default: path of page that created the cookie).
 * @option String domain The value of the domain attribute of the cookie (default: domain of page that created the cookie).
 * @option Boolean secure If true, the secure attribute of the cookie will be set and the cookie transmission will
 *                        require a secure protocol (like HTTPS).
 * @type undefined
 *
 * @name $.cookie
 * @cat Plugins/Cookie
 * @author Klaus Hartl/klaus.hartl@stilbuero.de
 */

/**
* Get the value of a cookie with the given name.
*
* @example $.cookie('the_cookie');
* @desc Get the value of a cookie.
*
* @param String name The name of the cookie.
* @return The value of the cookie.
* @type String
*
* @name $.cookie
* @cat Plugins/Cookie
* @author Klaus Hartl/klaus.hartl@stilbuero.de
*/
jQuery.cookie = function(name, value, options) {
if (typeof value != 'undefined') { // name and value given, set cookie
options = options || {};
if (value === null) {
value = '';
options.expires = -1;
}
var expires = '';
if (options.expires && (typeof options.expires == 'number' || options.expires.toUTCString)) {
var date;
if (typeof options.expires == 'number') {
date = new Date();
date.setTime(date.getTime() + (options.expires * 24 * 60 * 60 * 1000));
} else {
date = options.expires;
}
expires = '; expires=' + date.toUTCString(); // use expires attribute, max-age is not supported by IE
}
var path = options.path ? '; path=' + options.path : '';
var domain = options.domain ? '; domain=' + options.domain : '';
var secure = options.secure ? '; secure' : '';
document.cookie = [name, '=', encodeURIComponent(value), expires, path, domain, secure].join('');
} else { // only name given, get cookie
var cookieValue = null;
if (document.cookie && document.cookie != '') {
var cookies = document.cookie.split(';');
for (var i = 0; i < cookies.length; i++) {
var cookie = jQuery.trim(cookies[i]);
// Does this cookie string begin with the name we want?
if (cookie.substring(0, name.length + 1) == (name + '=')) {
cookieValue = decodeURIComponent(cookie.substring(name.length + 1));
break;
}
}
}
return cookieValue;
}
};

<sessionState mode="InProc" cookieName="ASP.NET_SessionId" cookieless="UseCookies"></sessionState>

Session["Key1"] = DateTime.Now;

<sessionState cookieName="SK"></sessionState>

this.labStatus.Text = (Request.IsAuthenticated ? "已登录" : "未登录");

<authentication mode="Forms" >
    <forms name="UserStatus"></forms>
</authentication>

private void SetLogin()
{
    System.Web.Security.FormsAuthentication.SetAuthCookie("fish", false);
}

private void SetLogout()
{
    System.Web.Security.FormsAuthentication.SignOut();
}

private void SetLogin()
{
    //System.Web.Security.FormsAuthentication.SetAuthCookie("fish", false);

// 下面的代码和上面的代码在作用上是等效的。
FormsAuthenticationTicket ticket = new FormsAuthenticationTicket(
2, "fish", DateTime.Now, DateTime.Now.AddDays(30d), false, string.Empty);
string str = FormsAuthentication.Encrypt(ticket);

HttpCookie cookie = new HttpCookie(FormsAuthentication.FormsCookieName, str);
Response.Cookies.Add(cookie);
}

private static string SendHttpRequestGet(string url, Encoding encoding, 
            CookieContainer cookieContainer)
    {
        if( string.IsNullOrEmpty(url) )
            throw new ArgumentNullException("url");

if( encoding == null )
throw new ArgumentNullException("encoding");

HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
request.Method = "GET";
request.CookieContainer = cookieContainer;

using( WebResponse response = request.GetResponse() ) {
using( StreamReader reader = new StreamReader(response.GetResponseStream(), encoding) ) {
return reader.ReadToEnd();
}
}
}

private void SendHttpDEMO()
{
StringBuilder sb = new StringBuilder();
CookieContainer cookieContainer = new CookieContainer();

string url = "http://www.taobao.com";
SendHttpRequestGet(url, Encoding.Default, cookieContainer);

// 后面可以继续发起HTTP请求，此时将会包含上次从服务器写入的Cookie
//SendHttpRequestGet("同域名下的其它URL", Encoding.Default, cookieContainer);

// 至此，我们可以显示取得了哪些Cookie
CookieCollection cookies = cookieContainer.GetCookies(new Uri(url));
if( cookies != null ) {
foreach( System.Net.Cookie cookie in cookies )
sb.AppendLine(cookie.ToString());
}
txtCookies.Text = sb.ToString();
}

/// <summary>
/// 用于方便使用Cookie的扩展工具类
/// </summary>
public static class CookieExtension
{
    // 我们可以为一些使用频率高的类型写专门的【读取】方法

/// <summary>
/// 从一个Cookie中读取字符串值。
/// </summary>
/// <param name="cookie"></param>
/// <returns></returns>
public static string GetString(this HttpCookie cookie)
{
if( cookie == null )
return null;

return cookie.Value;
}

/// <summary>
/// 从一个Cookie中读取 Int 值。
/// </summary>
/// <param name="cookie"></param>
/// <param name="defaultVal"></param>
/// <returns></returns>
public static int ToInt(this HttpCookie cookie, int defaultVal)
{
if( cookie == null )
return defaultVal;

return cookie.Value.TryToInt(defaultVal);
}

/// <summary>
/// 从一个Cookie中读取值并转成指定的类型
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="cookie"></param>
/// <returns></returns>
public static T ConverTo<T>(this HttpCookie cookie)
{
if( cookie == null )
return default(T);

return (T)Convert.ChangeType(cookie.Value, typeof(T));
}

/// <summary>
/// 从一个Cookie中读取【JSON字符串】值并反序列化成一个对象，用于读取复杂对象
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="cookie"></param>
/// <returns></returns>
public static T FromJson<T>(this HttpCookie cookie)
{
if( cookie == null )
return default(T);

return cookie.Value.FromJson<T>();
}

/// <summary>
/// 将一个对象写入到Cookie
/// </summary>
/// <param name="obj"></param>
/// <param name="name"></param>
/// <param name="expries"></param>
public static void WriteCookie(this object obj, string name, DateTime? expries)
{
if( obj == null )
throw new ArgumentNullException("obj");

if( string.IsNullOrEmpty(name) )
throw new ArgumentNullException("name");

HttpCookie cookie = new HttpCookie(name, obj.ToString());

if( expries.HasValue )
cookie.Expires = expries.Value;

HttpContext.Current.Response.Cookies.Add(cookie);
}

/// <summary>
/// 删除指定的Cookie
/// </summary>
/// <param name="name"></param>
public static void DeleteCookie(string name)
{
if( string.IsNullOrEmpty(name) )
throw new ArgumentNullException("name");

HttpCookie cookie = new HttpCookie(name);

// 删除Cookie，其实就是设置一个【过期的日期】
cookie.Expires = new DateTime(1900, 1, 1);
HttpContext.Current.Response.Cookies.Add(cookie);
}
}

public static class TestClass
{
    public static void Write()
    {
        string str = "中国";
        int aa = 25;
        DisplaySettings setting = new DisplaySettings { Style = 3, Size = 50 };
        DateTime dt = new DateTime(2012, 1, 1, 12, 0, 0);

str.WriteCookie("Key1", DateTime.Now.AddDays(1d));
aa.WriteCookie("Key2", null);
setting.ToJson().WriteCookie("Key3", null);
dt.WriteCookie("Key4", null);
}

public static void Read()
{
HttpRequest request = HttpContext.Current.Request;

string str = request.Cookies["Key1"].GetString();
int num = request.Cookies["Key2"].ToInt(0);
DisplaySettings setting = request.Cookies["Key3"].FromJson<DisplaySettings>();
DateTime dt = request.Cookies["Key4"].ConverTo<DateTime>();
}
}

public static class CookieValues
{
    // 建议把Cookie相关的参数放在一起，提供 get / set 属性（或者方法）来访问，以避免"key"到处乱写

public static string AAA
{
get { return HttpContext.Current.Request.Cookies["Key1"].GetString(); }
}
public static int BBB
{
get { return HttpContext.Current.Request.Cookies["Key2"].ToInt(0); }
}
public static DisplaySettings CCC
{
get { return HttpContext.Current.Request.Cookies["Key3"].FromJson<DisplaySettings>(); }
}
public static DateTime DDD
{
get { return HttpContext.Current.Request.Cookies["Key4"].ConverTo<DateTime>(); }
}
}

<authentication mode="Forms" >
    <forms name="MyCookieName" cookieless="UseCookies"></forms>
</authentication>

<httpCookies domain="www.123.com" httpOnlyCookies="true" requireSSL="false"/>

protected void Page_Load(object sender, EventArgs e)
{
    DateTime.Now.ToString().WriteCookie("t1", null);

label1.Text = ShowAllCookies();

Guid.NewGuid().ToString().WriteCookie("t2", null);

// 如果去掉下面代码，将会看到2个t1
Response.Cookies.Remove("t1");
Response.Cookies.Remove("t2");
}

private string ShowAllCookies()
{
StringBuilder sb = new StringBuilder();

for( int i = 0; i < Request.Cookies.Count; i++ ) {
HttpCookie cookie = Request.Cookies[i];
sb.AppendFormat("{0}={1}<br />", cookie.Name, cookie.Value);
}

return sb.ToString();
}